A typical machining apparatus for machining an elongated workpiece extending along a workpiece axis as disclosed in DE 10 2008 055 795 has a frame, a headstock mounted on the frame and capable of gripping one end of the workpiece and rotating the workpiece about a machining axis substantially parallel to or coinciding with the workpiece axis. A tailstock also carried on the frame is aligned with the machining axis so as to engage and center an opposite end of the workpiece gripped by the headstock for rotation of the workpiece about the machining axis, typically by powered rotation of the headstock about the machining axis. A machining drive carried on the frame carries a rotatable grinding disk or wheel engageable radially of the machining axis with the workpiece when the workpiece is engaged between the headstock and tailstock and rotating about the machining axis so as to machine the workpiece. The machining axis is typically vertical, and there may be two identical machining drives with grinding disks for machining diametrally opposite sides of the workpiece at the same time.
With this machine a separate dressing tool can be engaged with the grinding disk for dressing same. Thus the grinding disk and/or dressing tool can be shifted into engagement with each other to allow the working edge and/or face of the grinding disk to be trued. Thus for a dressing operation the machine must be reconfigured, entailing considerable down time.